We have a question and answers outlining the significant differences between the "big two" DSLR brands. I'm interested in the other DSLR makers, and how the cameras they make compare in terms of significant features, system design philosophy, and unique or interesting photographic capabilities enabled or made easier by these cameras. Likewise, what such things are not handled as well?

Take "the big two have more market share" and the associated advantages of availability, accessibility, and third-party support and documentation as a given.

I recognize this as in the subjective-question realm, but we've gotten constructive and positive response to the Canon/Nikon question, and I know we have a good representation of at least Pentax users on the site, so I hope we can do the same with this as a follow-up.
– Please Read My ProfileFeb 11 '12 at 13:59

5 Answers
5

As these camera makers own a smaller market share than Canon or Nikon, they have often tried more radical and innovative approaches than the big two. You can see both Canon and Nikon as more traditional makers with very consistent and proven features in their cameras.

When Sony bought Konica-Minolta's camera division, they inherited the only body-based stabilization system which they currently use in all their DSLRs and SLT cameras. Pentax and Olympus actually followed with their own version of the same.

In-body stabilization is the most significant difference between these brands and the big two as it stabilizes all lenses at no additional cost. There are some discussions regarding which type of stabilization is better but this is not only a cost saving feature (since you do not have to buy stabilization which each lens) but also an enabling feature since plenty of lenses have no stabilized equivalent (such as bright short primes and fisheyes).

Pentax goes one step further by using a magnetically suspended sensor and lets it rotate as well as shift. This gives them the unique ability to automatically correct for camera tilt (up to 2 degrees) and they can also shift the sensor to change perspective right in the camera. The just-announced mirrorless Olympus OM-D E-M5 will also be able to rotate its sensor.

Partly due to their smaller lens lineups, Pentax and Olympus have a smaller foothold in the pro market and therefore have developed fewer very high-end features including high-speed autofocus and continuous drives. The only DSLRs to shoot at 10 FPS or more are from Canon and Nikon. High-end Canon and Nikon cameras have more autofocus points than those used by Pentax, Sony and Olympus. Sony is on the fence here as having the only full-frame cameras among the smaller three manufacturers and their SLT models do shoot faster than 10 FPS.

Pentax builds some of the toughest DSLRs around and have the only ones rated to work below freezing (down to -10C or 14F). They have also introduced weather-sealing in their mid-range DSLRs along with matching lenses. With the Canon and Nikon, you need to buy rather expensive cameras and quite expensive lenses to get a weather-sealed system.

There are also different design philosophies among all manufacturers which is partly due to their target audience but also part of their identities, meaning sometimes something is done differently just to be different, not to be better. For example, Nikon lenses and dials rotate in the opposite direction as all other brands (although the dial direction is reversible on mid-to-high end models).

Pentax has the easiest cameras to use and theirs work in a very thoughtful way. For example, when using the 2s or 3s-Remote timer, Pentax DSLRs automatically perform mirror-lockup (MLU) and disable image stabilization. This is exactly what is needed when working from a tripod and takes more steps to do in other systems.

Sony DSLRs tend to have fewer features. While covering all the basics, they tend to be less customizable. Olympus on the other hand provides a high-level of customization even in entry-level models.

There are certainly tons of other design and feature differences which will be more or less significant depending on the type of photography you do. Particularly when it comes to flash and studio work.

I have a question about your penultimate point (pentax long exposure). It makes sense to turn on mirror lock-up and actually I'm envy of that! But what is the point of turning the IS off? Is it for sake of power saving or there is more to that?
– PouyaMar 13 '14 at 11:20

@Pouya - No, that is critically important. IS on a tripod can cause a feedback loop in which causes the camera to stabilize phantom movement which actually induces blur. This is extremely common with stabilized lenses as well although certain high-end offerings from Canon and Nikon have automatic tripod-detection or special tripod-mode for stabilization, this remains the exception rather than the norm. So you seem, you should be turning off stabilization when on a tripod and remember to turn it back on after.
– ItaiMar 13 '14 at 12:59

Thanks for the answer, but I'm afraid I didn't understand your answer completely. What do you think if post my doubt as a separate question? Could you kindly give me more in-depth explanation in that case?
– PouyaMar 17 '14 at 20:56

@Pouya - There are a number of related questions which you may look into like this one. Search for tripod stabilization to find more. Feel free to formulate the part you don't understand as a question.
– ItaiMar 17 '14 at 21:37

Having now used more than one brand (one pentax and one Nikon) - I think the statement "Pentax has the easiest cameras to use" cannot possibly be objective. While they (Pentax cameras) are not difficult to use, there are many, common actions that objectively require more button presses to navigate to than the equivalent Nikon. I'm not saying they're bad or that I won't eventually "get used to it", but objectively I don't think "easiest cameras to use" can be made because of more physical action required.
– rfuscaMar 18 '14 at 18:45

The only way to get autofocus Zeiss lenses1. While Zeiss makes lenses for Canon and Nikon mounts, they're strictly manual focus.

Yes, old Minolta lenses work -- and many are almost amazingly good on digital. Just for one example, there was a recent comparative review of the old (circa 1985) Minolta 70-210/4 to the current Canon 70-200/4L -- in which (at least according to that reviewer) the old Minolta did quite well. I feel obliged to add that the reviewer in question is generally a Minolta advocate so there's probably some bias -- but the pictures he includes do seem to support his conclusions at least reasonably well.

Focus Peaking. The recent SLT models have a focus-peaking mode, where the EVF and/or LCD will highlight what parts of the picture are in focus.

Although some people obviously disagree, as far as I can tell, Nikon's are really only designed for people who are ambidextrous, and Canon's seem to have been designed for some alien race with hands that have each have 2 (or maybe three) thumbs and 6 fingers, all with lengths quite a bit different from any human's (i.e., Nikon has a habit of requiring you to do things with both hands at once to accomplish things, while Canon seems (to me) to just scatter buttons almost randomly, so things get changed by accident constantly, but are hard to reach and/or manipulate when you need them).

Higher color saturation and accuracy. Nikon and (especially) Canon use "thinner" (less saturated) color filters on their sensors. This reduces noise but also reduces the range of colors they can sense.

Mirror lockup implemented for actual use instead of (apparently) to just fill in a spot on the feature list (e.g., most Canons that have mirror lockup at all bury it under a custom function menu where it's hard to find and harder to use).

At least to me, one of the most important features is really the lens selection. Unlike most brands, where lens selection is almost entirely about sheer numbers, with Sony you get a choice of character.

Back when German companies produced all the best cameras/lenses, Zeiss produced the sharpest, highest contrast, most technically advanced lenses you could get. Leica's lenses had lower contrast but high micro-contrast, designed more toward taking "prettier" pictures.

At one time, Minolta was closely associated with Leica2 and followed a a similar lens design philosophy. Sony, on the other hand, has used Zeiss lenses on most of their pro video cameras for quite a while, and now has Ziess lenses for their still cameras as well.

As such, lens selection for Sony cameras isn't just about buying the best lenses you can get, but about selecting lenses to express your vision for a particular photograph (or type of photograph). When you want the almost-glowing look of a Leica, you can get that with the older Minolta lenses. When you want the sharpest, most detailed, highest contrast, etc., pictures, the Sony Zeiss lenses will be a better fit. I suppose I should add, however, that buying both could get just a bit expensive. Most people consider one 85/1.4 (for example) a pretty expensive lens; few are likely to buy both a Minolta 85/1.4G and a Sony/Zeiss 85/1.4 ZA (though if I could afford it, I probably would have and use both).

If you want to get really technical, there were also a few Contax/Yashica AF Zeiss lenses, but they've all been obsolete for quite a while. Excellent lenses, but your body choices are film or one digital body, which may be the best 6 MP camera ever built, but it's hardly competitive with anything recent.

Closely enough that, for example, Leica CL and CLE cameras were actually made by Minolta.

@mattdm: Unfortunately, it's hard to find any such thing online. Most tests (e.g., DxO) use the Gretag Macbeth color checker (or something on the same order), which doesn't have any really saturated colors. Lack of saturated colors in the test obviously makes it hard to show any such thing in the results.
– Jerry CoffinApr 1 '12 at 17:30

FWIW - Minolta made & Sony for some while continued an 500 mm f/8 Reflex aka mirror lens. This is the ONLY AF mirror lens ever made and with in body stabilisation is thus the only AF stabilised mirror lens ever made. While generally not up to the standards of a REALLY good 500 mm refracting lens it is far lighter and far more compact than any "normal" lens and is suitable for carrying when weight and size are at a premium. (When I travel internationally on business I usually take a wide range zoom, an f/8 mirror and a 50mm f/1.8 - more if circumstances allow. )
– Russell McMahonDec 31 '13 at 12:12

as Itai's answer was very detailed, I will only add some details regarding to Pentax, which at least for me were important when buying my first DSLR:

1) support for AA batteries in Pentax entry level DSLR - some people love it, some hate it ... (I am from the first group :-) ) - currently you can decide as newest K-r supports both.

2) Pentax has excellent backwards compatibility with old lenses and even with old manual lenses there is not problem to use exposition metering and something like AF detection - we call it "shooting on the swing" - I do not remember the english name for this feature, but you press the trigger and move to and from the object and the camera takes a picture just when it detects focus. I found it very helpful when shooting with old Pentacon lens.

Olympus
I though bout Olympus as they have double zoom kits for very good price. However, they have even worse selection of supported 3rd party lenses than Pentax and Sony and original Olympus lenses are expensive for entry level hobby users.

Have no experience with Sony DSLRs. They have those nice EXMOR chips with low noise, but Pentax now uses them too :-) As I know, they should be compatible with old Minolta lenses.

Sigma fits well with the "smaller camera makers can be more experimental" theme: Their primary claim to uniqueness is that the Sigma DSLRs are using a different type of sensor, the Foveon X3, which has higher per-pixel color resolution than the standard Bayer filter sensor.

A little background:
Almost all DSLRs use a type of sensor called a Bayer filter, where each photosite (called a pixel) is sensitive to only one color, in a 25% red / 50% green /25% blue pattern:

So the actual color resolution of a Bayer sensor is at best half (green) and at worst a quarter (red and blue) of the sensor pixel count. To produce a full RGB image with the same pixel count, the missing values are derived from surrounding pixels in a process called demosaicing, similar to Photoshop interpolation.
Bayer sensors are sensitive to color aliasing (moiré), so a lowpass filter is normally placed in front of the sensor to reduce it, this sacrifices a little resolution/sharpness.

By contrast, the Foveon sensor records all colors at every pixel.
The Foveon sensor is also less sensitive to moiré, so it can skip the low-pass filter and gain a little extra sharpness.

There is no doubt that the Foveon sensor has inherently higher color resolution on a per-sensor-pixel basis. How much higher is a matter of debate, see e.g.

Owning several Pentax (K20D, K-5, K-3) and a Sony (SLT A55V), I can add a little to Itai's:

Pentax has a unique gimmick: An add-on GPS device (well, my Sony has GPS already built in), the O-GPS1, that is able to track stars. So, if you like to experiment with shooting stars at night, this is quite a great accessory. You can find example images on Flickr (tag: Astrotracer) and on Pentaxforums.com.

All Pentax DSLRs have two dials - one in front, one at the rear, and you can configure them, individually for each exposure mode (P, Av, Tv, X, M etc.) to control either time, aperture, exposure shift or ISO values directly. Very convenient - e.g, in P mode, it usually selects a middle value for T and A, but if you don't like it in a particular situation, you simply turn one of the dials to immediately change A or T to a chosen value. No need to switch from P to A or T for that.

There are a lot of customization options. E.g, If you are using a flash (internal or external), you can choose whether you want to take a shot if the flash is not ready yet at the time you press the shutter button - if you allow it, it'll take the shot as if the flash was off, with adequate exposure. For P mode, you can preset the preference for the choices of ISO, T and A: Speed (short T), small or large aperture, MTF (optimal A for lens). Can't say if the other brands offer so many choices, though my (cheap) Sony at least doesn't.

The new top-of-the line model, the Pentax K-3, now enables remote control (including Live View) abilities with the "Flu Card" as an accessory. Though, as of now, its flexibility is far from what the pro models from Canikon offer.

Like Sony, the Pentax K-3 now also has focus peeking in Live View. Older models don't, though.

As for the entry-level Sony models, I can say about mine that it is significantly lighter than any Pentax DSLR. There are also light zoom lenses from Sony. This is of advantage if you tend to travel with your camera in your bag or backpack.

The swiveling rear monitor on the Sony SLTs can be useful as well. Pentax does not offer this at all so far. OTOH, I can connect a portable LCD monitor to my Pentax via its HDMI output if I need the flexility, e.g. for macro shooting.

The Sonys, not being true SLRs (because they do not use a fold-up mirror) can, due to their design, focus faster while recoding video or taking shots in rapid succession ("drive mode") because they can use phase-detection sensors while the sensor is recording. Pentax can't do this quite as well.